The swallowing process is, to a large extent, a mechanical one. Although a great deal is known biologically about the esophageal phase of bolus transport, no mechanical analysis directly modeling esophageal bolus transport has been carried out - biological studies concentrate, by and large, on anatomical descriptions. The primary mechanical variable used clinically is the contractile amplitude, or peak force of esophageal wall squeeze, obtained manometrically. With a completely occluding peristaltic wave, however, the contractile amplitude has no direct relevance to the intrabolus forces generated in the transport process. It is the intention of the proposed study to describe those mechanical variables which directly describe esophageal bolus transport; to quantify the relationships and sensitivities among these mechanical variables during peristalsis; to establish the biological bounds in the relationships among the mechanical variables during normal esophageal bolus transport, and modifications associated with mechanical abnormality; and to describe the biological relationship (if it exists) between mechanical variables associated with bolus transport, and the contractile amplitude. In collaboration with Drs. Wylie Dodds and James Helm of the Medical College of Wisconsin, numerical simulation and mathematical analysis will be combined with biological data in human subjects to develop mechanical models of esophageal bolus transport. The mathematical models emphasize fundamental understanding, and will be used to validate the general numerical procedure. A numerical "laboratory" will be developed for detailed mechanical analysis of the esophageal transport process, and for long term study. Radiographic data will provide boundary inputs to the model, and simultaneous manometric measurements of intrabolus pressure will be compared with numerical predictions. Detailed analysis will be carried out, and the mechanical relationships described above established, placing special emphasis on variations associated with mechanical abnormalities. A future goal is to couple the bolus model with one for the esophageal wall, including, as a major element, active wall control of bolus transport.